Founded with the intent of collecting copies of or links to as many primary documents from the period of the secession crisis as is reasonably possible, with the goal of shedding light on the causes of secession, hence of the war.
http://members.aol.com/jfepperson/causes.html

1,118 photographs of the Civil War, including scenes of military personnel, preparations for battle, and battle after-effects. The collection also includes portraits of both Confederate and Union officers, and a selection of enlisted men. From the Prints and Photographs Division of the Library of Congress.
http://lcweb2.loc.gov/ammem/cwphome.html